246681-YTG-B-0607
4
Unitary Products Group
APPLICATIONS
Unitized Energy Recovery Ventilators (UERV) are used with
the York rooftop packaged units. The internal wheel provides
sensible and latent energy exchange between the entering
and exhaust air streams of a building. This allows a substan-
tial amount of the energy, which is normally lost in the
exhaust air stream to be returned into the entering air. Ideal
applications are areas that have cold or hot temperatures, or
areas that have high humidity or very low humidity (recover
exhaust air from buildings that have humidifiers to add
humidity). Application software is available to provide the
energy and dollar savings for all areas of the United States
and Canada.
PRINCIPLE OF OPERATION
The UERV enthalpy wheel contains parallel layers of a poly-
meric material that are impregnated with silica gel (desic-
cant). The wheel is located in the entering (intake) air and
exhaust air streams of the ventilation equipment. As the
wheel rotates through each air stream, the wheel surface
adsorbs sensible and latent energy. In the heating mode, the
wheel rotates to provide a constant transfer of heat from the
exhaust air stream to the colder intake air stream. During the
cooling season, the process is reversed. On units equipped
with an economizer (3 - 12.5 tons), the wheel pivots out of the
air stream to allow economizer to operate normally for "free
cooling" when outdoor temperature and humidity is accept-
able. During economizer operation, the UERV exhaust
blower continues to run, providing power exhaust for the sys-
tem. The intake blower is de-energized during economizer
operation.
ARI STANDARD 1060-2000 FOR AIR-TO-AIR
ENERGY RECOVERY VENTILATION EQUIPMENT
The Air-Conditioning and Refrigeration Institute (ARI) issued
Standard 1060-2000 to certify air-to-air energy recovery ven-
tilators. This standard deals specifically with the ratings of the
Energy Recovery Wheel that is incorporated into the Energy
Recovery Ventilator (ERV). All of the York ERV's have an ARI
certified energy recovery wheel. The data shown in the spec-
ification charts is the ARI certified ratings for the wheel.
Actual performance in the ERV may vary.
Critical Terms for Standard 1060 are as follows:
1.
Effectiveness
. The measured energy recovery effec-
tiveness not adjusted to account for that portion of the
psychrometric change in the leaving supply air (Station
2) that is the result of leakage of entering exhaust air
(Station 3) rather than exchange of heat or moisture
between the air streams.
2.
Net Effectiveness
. The measured recovery effective-
ness adjusted to account for that portion of the psycho-
metric change in the leaving supply air (Station 2) that is
the result of leakage of the entering exhaust air (Station
3) rather than exchange of heat or moisture between the
air streams.
3.
Exhaust Air Transfer Ratio (EATR)
. The tracer gas
concentration difference between the leaving supply air
(Station 2) and entering supply (outdoor) air stream (Sta-
tion 1) divided by the tracer gas concentration in the
entering exhaust (return) air (Station 3) at the 100%
rated air-flow, expressed as a percentage.
4.
Outdoor Air Correction Factor (OACF)
. The entering
supply (outdoor) airflow (Station 1) divided by the mea-
sured (gross) leaving supply airflow (Station 2).
ENERGY RECOVERY WHEEL
The heart of the Energy Recovery Ventilator is the Energy
Recovery Wheel (defined by ARI as a rotary heat exchanger).
The wheel has a patented design of parallel layers of
wrapped polymeric material that is impregnated with a silica
gel (desiccant). This unique design makes it the only truly
cleanable wheel on the market today. The small wheels (30
inch diameter and smaller) are slide out cassettes, and the
larger wheels have pie segments that are removable for
cleaning.
FIGURE 1 - UNITIZED ENERGY RECOVERY
VENTILATOR
FIGURE 2 - ENERGY RECOVERY WHEEL
